# 关于前缀树的解释：https://www.cnblogs.com/luosongchao/p/3239521.html


class TrieNode(object):
    def __init__(self):
        self.childs = dict()
        self.isword = False
class Trie(object):

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.root = TrieNode()



    def insert(self, word):
        """
        Inserts a word into the trie.
        :type word: str
        :rtype: None
        """
        node = self.root
        for letter in word:
            if node.childs.get(letter):
                node = node.childs[letter]
            else:
                node.childs[letter] = TrieNode()
                node = node.childs[letter]
        node.isword = True

    def search(self, word):
        """
        Returns if the word is in the trie.
        :type word: str
        :rtype: bool
        """
        node = self.root
        for letter in word:
            if node.childs.get(letter):
                node = node.childs[letter]
            else:
                return False
        return node.isword

    def startsWith(self, prefix):
        """
        Returns if there is any word in the trie that starts with the given prefix.
        :type prefix: str
        :rtype: bool
        """
        node = self.root
        for letter in prefix:
            if node.childs.get(letter):
                node = node.childs[letter]
            else:
                return False
        return True
# Your Trie object will be instantiated and called as such:
# obj = Trie()
# obj.insert(word)
# param_2 = obj.search(word)
# param_3 = obj.startsWith(prefix)